summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/machine/7474.h
diff options
context:
space:
mode:
Diffstat (limited to 'src/emu/machine/7474.h')
-rw-r--r--src/emu/machine/7474.h63
1 files changed, 63 insertions, 0 deletions
diff --git a/src/emu/machine/7474.h b/src/emu/machine/7474.h
new file mode 100644
index 00000000000..77ada157ce7
--- /dev/null
+++ b/src/emu/machine/7474.h
@@ -0,0 +1,63 @@
+/*****************************************************************************
+
+ 7474 positive-edge-triggered D-type flip-flop with preset, clear and
+ complementary outputs. There are 2 flip-flops per chips
+
+
+ Pin layout and functions to access pins:
+
+ clear_w [1] /1CLR VCC [14]
+ d_w [2] 1D /2CLR [13] clear_w
+ clock_w [3] 1CLK 2D [12] d_w
+ preset_w [4] /1PR 2CLK [11] clock_w
+ output_r [5] 1Q /2PR [10] preset_w
+ output_comp_r [6] /1Q 2Q [9] output_r
+ [7] GND /2Q [8] output_comp_r
+
+
+ Truth table (all logic levels indicate the actual voltage on the line):
+
+ INPUTS | OUTPUTS
+ |
+ PR CLR CLK D | Q /Q
+ --------------+-------
+ L H X X | H L
+ H L X X | L H
+ L L X X | H H (Note 1)
+ H H _- X | D /D
+ H H L X | Q0 /Q0
+ --------------+-------
+ L = lo (0)
+ H = hi (1)
+ X = any state
+ _- = raising edge
+ Q0 = previous state
+
+ Note 1: Non-stable configuration
+
+*****************************************************************************/
+
+#ifndef TTL7474_H
+#define TTL7474_H
+
+
+/* The interface structure */
+struct TTL7474_interface
+{
+ void (*output_cb)(void);
+};
+
+
+void TTL7474_config(int which, const struct TTL7474_interface *intf);
+
+/* must call TTL7474_update() after setting the inputs */
+void TTL7474_update(int which);
+
+void TTL7474_clear_w(int which, int data);
+void TTL7474_preset_w(int which, int data);
+void TTL7474_clock_w(int which, int data);
+void TTL7474_d_w(int which, int data);
+int TTL7474_output_r(int which);
+int TTL7474_output_comp_r(int which); /* NOT strictly the same as !TTL7474_output_r() */
+
+#endif